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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
      
        // var str="13813081308,13951395171,13770077118"
        // console.log(str.split(","))
        // var str="122222222222222222222222222"
        // console.log(str.replace(str.substring(5),"..."))
        // console.log(str.substr(3,4))
        // console.log(str.replace(str.substr(3,4),"****"))

        /*
            var left=str.substr(0,3)
            var middle="*".repeat(4)
            var right=str.substr(7)
            var all=left+middle+right
            console.log(all)
        */
         // ...
        // 随机给一个字符串 如果长度大于5 就用省略号代替...
        // 如果不大于，就直接打印原来的字符串
        /*
            var suiji ="122222222222222222222222222"
            if(suiji.length>5){
                var suiji=suiji.substr(0,5)+"..."
                console.log(suiji)
            }else{
                console.log(suiji)
            }
        */

        // var str="helloworld"

        // console.log(str[0].toUpperCase()+str.substr(1))

        // var suiji="rtfgohwkefhlkwqeflhhweqy123hjnjjnf,q"

        //写出每一个字符的个数

        



        
    </script>
</body>
</html>